Capacitor with improved heat dissipation

ABSTRACT

A capacitor comprises a first winding member, where the first winding member comprises a first dielectric layer and a first conductive layer. A second winding member comprises a second dielectric layer and second conductive layer. The first winding member is interleaved, partially or entirely, with the second winding layer. A dielectric package is adapted to at least radially contain or border the first winding member and the second winding member. A first metallic member has a generally planar, radially extending surface for electrically and mechanically contacting an upper portion the first conductive layer. A second metallic member has a generally planar, radially extending surface for electrically and mechanically contacting a lower portion of the second conductive layer.

RELATED APPLICATIONS

This is a continuation of U.S. application Ser. No. 14/529,337, filedOct. 31, 2014, which is hereby incorporated by reference.

FIELD OF THE INVENTION

This disclosure relates to a capacitor with improved heat dissipation oran electronic assembly with one or more capacitors with improved heatdissipation.

BACKGROUND

In certain prior art, a capacitor or an electronic assembly thatincorporates one or more capacitors may have inadequate heat dissipationthat reduces the longevity or maximum power output of an electroniccircuit. For certain film capacitors, the heat dissipation is limited bythe package design of the capacitor. Accordingly, there is need for acapacitor or electronic assembly with improved heat dissipation.

SUMMARY

In one embodiment, a capacitor comprises a first winding member, wherethe first winding member comprises a first dielectric layer and a firstconductive layer. The first conductive layer overlies at least a portionof the first dielectric layer. A second winding member comprises asecond dielectric layer and second conductive layer. The secondconductive layer overlies at least a portion of the second dielectriclayer. The first winding member is interleaved, partially or entirely,with the second winding layer. A dielectric package or shell is adaptedto at least radially contain or border the first winding member and thesecond winding member. A first metallic member has a generally planar,radially extending surface for electrically and mechanically contactingan upper portion the first conductive layer. A second metallic memberhas a generally planar, radially extending surface for electrically andmechanically contacting a lower portion of the second conductive layer.A first lead is coupled to the first metallic layer and extends throughan upper side surface. In one embodiment, an optional second leadextends through the upper side surface, where the second lead is spacedapart from the first lead. However, in other embodiments the second leadis not required because the second metallic member can be exposed toserve as an auxiliary lead.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of an electronic assemblywith capacitors arranged in rows and one capacitor shown in an explodedformat separate from the electronic assembly (without any enclosure).

FIG. 2 is a plan or top view of single capacitor of FIG. 1 thatillustrates interior windings as dashed lines.

FIG. 3 shows a cross-section of the capacitor of FIG. 2 along referenceline 3-3 of FIG. 2.

FIG. 4 shows a perspective view of a bottom of a capacitor of FIG. 2.

FIG. 5 illustrates a plan or top view of another embodiment of acapacitor that illustrates the interior windings in phantom.

FIG. 6 shows a cross-section of the capacitor of FIG. 5 along referenceline 6-6 of FIG. 5.

FIG. 7 shows a perspective view of a bottom of a capacitor of FIG. 5.

FIG. 8 shows a cross-section of an electronic assembly that is housed inan enclosure.

FIG. 9 illustrates a plan or top view of another embodiment of acapacitor that illustrates the interior windings in phantom.

FIG. 10 shows a cross-section of the capacitor of FIG. 9 along referenceline 10-10 of FIG. 9.

FIG. 11 shows a perspective view of a bottom of a capacitor of FIG. 9.

Like reference numbers in different drawings indicate like elements.

DETAILED DESCRIPTION

A package of the capacitor 10 comprises one or more leads (e.g., 22,24), terminals, or electrodes and an enclosure, shell or skin. Thepackage may be configured for optimal or improved heat dissipation ofthermal energy from the capacitor 10 to the ambient environment, acircuit board 28 upon which the capacitor 10 is mounted, or an enclosure(800 in FIG. 8) or housing in which the capacitor 10 is housed, forexample. The capacitor 10 may be made or constructed as a filmcapacitor, or otherwise.

FIG. 1 illustrates one embodiment of an electronic assembly 11 thatcomprises a circuit board 28 having one or more conductive traces andone or more capacitors 10 mounted on the circuit board 28. The circuitboard has a first side 30 and a second side 32 opposite the first side30. As shown, the capacitors 10 are arranged in one or more rows (26,34) on both sides (30, 32) of the circuit board 28, but the capacitors10 may be arranged in other configurations on one or both sides (30, 32)of the circuit board 28. The circuit board 28 may have one or moreconnectors, such as one or more metal connectors 38 or a multi-conductorconnector 36.

Capacitors 10 may be soldered to a circuit board 28, such as a printedcircuit board 28. In one configuration, the circuit board 28 isoptionally constructed with heavy traces (e.g., equal to or greater than8 ounce traces or having a thickness greater than the ordinary metallictraces on the circuit board 28) to conduct sufficient amounts ofelectrical current for certain power electronic circuits. Mounting thecapacitors 10 to the circuit board 28 in this fashion allows for heat tobe transferred or communicated from the bottom 20 of the capacitor 10,through the circuit board 28, to any heat sink or heat-sinking enclosureassociated with the circuit board 28.

As illustrated in FIG. 2 and FIG. 3, in one embodiment a capacitor 10comprises a first winding member 50 and a second winding member 52. Thefirst winding member 50 is interleaved, partially or entirely, with thesecond winding layer. In one embodiment, the first winding member 50comprises a first dielectric layer 42 and a first conductive layer 39.The first conductive layer 39 overlies at least a portion of the firstdielectric layer 42. A second winding member 52 comprises a seconddielectric layer 37 and second conductive layer 40. The secondconductive layer 40 overlies at least a portion of the second dielectriclayer 42.

A dielectric package 12 is adapted to at least radially contain orborder the first winding member 50 and the second winding member 52. Adielectric package 12 contains radially or borders radially the firstwinding member 50 and the second winding member 52. The dielectricpackage 12 may comprise a dielectric skin or dielectric shell, forexample.

A first metallic member 54 has a generally planar, radially extendingsurface for electrically and mechanically contacting an upper portionthe first conductive layer 39. A second metallic member 56 has agenerally planar, radially extending surface for electrically andmechanically contacting a lower portion of the second conductive layer40. A first lead 22 is coupled to the first metallic member 54 andextends through an upper side surface 14.

In one configuration, the first dielectric layer 42 and the seconddielectric layer 37 are formed of polyethylene, a plastic, or polymerthat is substantially elastically deformable or generally pliable. Thefirst conductive layer 39 and the second conductive layer 40 can be ametal foil layer or a metallized layer that is formed by electro-lessdeposition, sputtering, plating or other process. The first windingmember 50 has a side margin of the first dielectric layer 42 that is notmetallized or covered by a first conductive layer 39; the second windingmember 52 has a side margin that is not metallized or covered by asecond conductive layer 40, where the first winding member 50 and thesecond winding member 52 are stacked on top 16 of each other and woundaround dielectric bobbin or form (e.g., a removable or captive form).

FIG. 2 and FIG. 3 show a capacitor 10 in accordance with the disclosure.The capacitor 10 has leads coming out the top 16 of the capacitor 10 aswell as a metallic pad placed on the bottom 20 of the film capacitor 10.The bottom 20 of the capacitor 10 has the second metallic member 56 ormetallic pad connected to the second winding member 52 (or the secondconductive layer 40) for improved thermal dissipation. Similarly, theconnection leads are formed in a substantially planar configuration nearor at the top 16 of the capacitor 10 for improved heat dissipation. Thiscapacitor 10 has been designed for optimal heat transfer from the bodyof the capacitor 10 via thermally efficient axial heat flow via thefirst metallic member 54, the second metallic member 56, and associatedleads. The second metallic member 56 or exposed metallic pad on thebottom 20 of the cap can be soldered or placed in contact (e.g.,directly or indirectly with thermally conductive material or grease)with a surface, receiving pad, or conductive trace that can transferheat (e.g., to a heat sink or enclosure 800). The top 16 of thecapacitor 10 has also been designed as to allow the flat configuredleads (22, 24) to press up against a heat sink or enclosure 800 andremove heat generated in or by the capacitor 10. The leads (22, 24) arethen configured to allow the electrical connection and mechanicalconnection to be made to the circuit board 28. In an alternateembodiment, the capacitor 10 can also be made to work without the bottom20 having a metallic interface or exposed metallic pad for direct orindirect contact with a receiving pad, heat sink or traces on thecircuit board 28.

As best illustrated in FIG. 3 and FIG. 4, the dielectric package 12 hasor is associated with an upper side surface 14 and a lower side surface18 opposite the upper side surface 14. A first metallic member 54 has agenerally planar, radially extending surface (e.g., first annularsurface) for electrically and mechanically contacting an upper portionof the first conductive layer 39. A second metallic member 56 has agenerally planar, radially extending surface (e.g., second annularsurface) for electrically and mechanically contacting a lower portion ofthe second conductive layer 40. A first lead 22 is coupled to the firstconductive layer 39, via first metallic member 54, and extends throughthe upper side surface 14. A second lead 24 extends through the upperside surface 14. The second lead 24 is spaced apart from the first lead22. In one embodiment, the second lead 24 is coupled to an upper portionof the first conductive layer 39 via the first metallic member 54.

The dielectric package 12 has a lower side surface 18 opposite the upperside surface 14. The first lead 22 has generally planar upper surfaces51 substantially parallel to or co-planar to the upper side surface 14and generally planer lower surfaces 53 parallel or co-planar to thelower side surface 18. The second lead 24 has generally planar uppersurfaces 51 substantially parallel to or co-planar to the upper sidesurface 14 and generally planar lower surfaces 53 substantially parallelor co-planar to the lower side surface 18. In one embodiment, the firstlead 22 and the second lead 24 each terminate in a metallic pad 55 formounting a mating pad or conductive trace on a circuit board. Thedielectric package 12 has a lower side surface 18 opposite the upperside surface 14; the lower side surface 18 comprises the second metallicmember 56 with an exposed exterior surface or a metallic pad. FIG. 4illustrates an exposed metallic pad associated with the second metallicmember 56. The metallic pad can be soldered to a corresponding mountingpad or conductive trace on the circuit board 28. In one embodiment, thesecond metallic member 56 has its perimeter covered or bonded to adielectric perimeter member 57 or wall.

FIG. 2 and FIG. 3 illustrates how the space-saving leads (24, 26) arebent as to occupy the so-called corners of the capacitor 10. In astandard design (not shown), a film capacitor would be placed in arectangular plastic container or box that is filled with epoxy to securethe windings. In the configuration, the rectangular box of the capacitor10 has been replaced with a generally elliptical configuration (e.g.,elliptical, cylindrical, or oblong shaped container) as to make use ofthe corner space and to minimize the overall mounting footprint of thecapacitor 10. The footprint is reduced because if the capacitor 10 wherehoused in a square box the lead would have to extend outside of thisfootprint. FIG. 1 illustrates how rows (26, 34) of capacitors 10 arenested together, in close proximity, to construct a capacitor bank, withthe space-saving lead configuration (22, 24).

FIG. 5 through FIG. 7, illustrate an alternative embodiment of a 110capacitor. The 110 capacitor of FIG. 5 through FIG. 7 is similar to thecapacitor 10 of FIG. 2 through FIG. 4, except the second lead 124 ofFIG. 6 differs from the second lead 24 of FIG. 3. Like reference numbersin FIG. 1 through FIG. 7, inclusive, indicate like elements.

As illustrated in FIG. 5 and FIG. 6, the first lead 22 is connected tothe upper portion of the first conductive layer 39 via the firstmetallic member 54 at connection point 129, for example. The second lead124 is coupled to a lower portion of the second conductive layer 40 viathe second metallic member 56 and internal conductor 127. The secondmetallic member 56 may or may not be exposed in the capacitor of FIG. 5through FIG. 7. For example, in FIG. 7 the second metallic member 56 iscovered with bottom dielectric member 157, which may be integral orcontinuous with the dielectric package 12.

FIG. 8 illustrates the electronic assembly 11 of FIG. 1 that is housedin an enclosure 800. In FIG. 1, the enclosure 800 is omitted to bettershow the electronic assembly 11. Like reference numbers in FIG. 1 andFIG. 8 indicate like elements.

FIG. 8 illustrates an enclosure 800 for housing the electronic assembly11, although any other housing or case may be made to house or surroundthe capacitors (e.g., 10, 110, or 210) to effectively conduct ortransfer heat from the top 16 of the leads (e.g., 22, 24, 124). In thisconfiguration, the enclosure has a first enclosure portion and a secondenclosure portion that are mirror images of each other. The circuitboard 28 has capacitors (e.g., 10, 110, or 210) on the first side 30,the second side 32, or both.

As illustrated in FIG. 8, the enclosure 800 comprises a first innerenclosure portion 801, a first outer enclosure portion 805, a secondinner enclosure portion 802 and a second outer enclosure portion 806.The first inner enclosure portion 801 and the second inner enclosureportion 802 can be joined together with fasteners, adhesive, or anothersecuring mechanism to hold or house the electronic assembly 11. Thefirst outer enclosure portion 805 is capable of mating or sealing withthe first inner portion 801 such that coolant or fluid may be retainedor circulated within a chamber, conduit or passageway formed by thejoining of the first outer enclosure portion 805 and the first innerenclosure portion 801. The second outer enclosure portion 806 is capableof mating or sealing with the second inner portion 802 such that coolantor fluid may be retained or circulated within a chamber, conduit orpassageway formed by the joining of the second outer enclosure portion806 and the second inner enclosure portion 802. In FIG. 8, illustrativearrows (803, 804) show where the fluid or coolant (e.g., water orethylene glycol, or a solution thereof) would flow to cool thecapacitors (e.g., 10, 110 or 210).

The first inner enclosure portion 801 engages or contacts first leads 22and second leads (e.g., 24 or 124, if present) of a first set (e.g.,rows 26) of capacitors (e.g., 10, 110 or 210) such that heat can axiallyflow away (e.g., upward) from the electronic assembly 11 via theenclosure 800. The second inner enclosure portion 802 engages orcontacts first leads 22 and second leads 24 of the second set (e.g.,rows 34) of capacitors (e.g., 10, 110, 210) such that heat can axiallyflow away (e.g., downward) from the electronic assembly 11 via theenclosure 800. The fluid or coolant may transfer or remove heat from theelectronic assembly 11 or the capacitors (e.g., 10, 110, 210) bycirculating or pumping the fluid through a radiator to the ambient air,for example. Further, mounting or soldering the capacitors (e.g., 10,110 or 210) to the circuit board 28 via pads 55, an exposed portion ofthe second metallic member 56, or both allows for heat to be transferredor conducted away from the bottom 20 of the capacitor, through thecircuit board 28, as well as through the top 16 of the capacitor 10 viaa heat sink (e.g., fluid-cooled heat sink or chamber) above thecapacitors.

In an alternate embodiment, a thermal interface material (TIM, not shownin FIG. 8) may be inserted or placed between the capacitor leads (e.g.,22, 24, 124) or top 16 of the capacitor (e.g., 10, 110 or 210) and thefirst inner enclosure portion 801 or the enclosure 800. Similarly, TIMmay be inserted or placed between the capacitor leads (e.g., 22, 24,124) or bottom 18 of the capacitor through the circuit board 28 via theheat sink (e.g., fluid-cooled heat sink or chamber) below thecapacitors. A thermal interface material (TIM) may comprise a polymer,elastomer, adhesive, or plastic, such as silicone. The thermal interfacematerial may be injected, injected molded or forced into any air gapbetween the capacitor. The TIM can provide dielectric insulation betweenthe terminals (22, 24) and the enclosure 800 of the assembly. The TIMmay also fill gaps between adjacent ones of the capacitors (e.g., 10,110, or 210) to provide cooling to the printed circuit board 28 viaconduction of heat outward toward the enclosure 800.

FIG. 9 through FIG. 11, inclusive, provides an illustration of anotheralternate embodiment of a capacitor 210. The capacitor 210 of FIG. 9through FIG. 11, inclusive, is similar to the capacitor 10 of FIG. 1through FIG. 3, inclusive, except the second lead 24 is eliminated andthe exposed metallic pad of the second metallic member 56 is used as anauxiliary terminal or terminal for the capacitor 210. The second lead 24is not required because the second metallic member 56 can be exposed toserve as an auxiliary lead or electrode. The bottom 20 of the capacitor210 has an optional exposed metallic surface or metal pad that providesadditional heat sinking for greater power dissipation (e.g., inpotentially smaller packages of the capacitor 210 than otherwisepossible).

In any embodiments set forth in this document, the capacitor andelectronic assembly are well-suited for securing certain capacitors(e.g., medium to small size capacitors) directly to a circuit board,while supporting thermal heat dissipation from the capacitor. Heat candissipate or flow from the bottom of the capacitor, directly orindirectly, through the circuit board and then to the enclosure. Forexample, an exposed pad of the second metallic member (e.g., 56) mayprovide a surface for efficient heat transfer to a metallic trace ormetallic pour (e.g. heavy copper pour) on the circuit board. Heat canalso dissipate or flow from the top of the capacitor, directly to theenclosure or to ambient air. The enclosure may comprise a heat sink witha jacket or coolant chamber for cooling the enclosure, one or morecapacitors and an electronic assembly.

The leads of the capacitor are also arranged for efficient thermaldissipation to ambient air, the enclosure and the circuit board viacorresponding pads or conductive traces. Because one or more capacitorsof the electronic assembly can be kept cooler, the electronic assembly(e.g., such as an inverter or controller) can operate reliably over alonger lifespan or have greater current or power handling capacity thanotherwise possible.

Having described the preferred embodiment, it will become apparent thatvarious modifications can be made without departing from the scope ofthe invention as defined in the accompanying claims.

The invention claimed is:
 1. A capacitor comprising: a first windingmember comprising a first dielectric layer and a first conductive layer,the first conductive layer overlying at least a portion of the firstdielectric layer; a second winding member comprising a second dielectriclayer and second conductive layer, the second conductive layer overlyingat least a portion of the second dielectric layer, the first windingmember interleaved, partially or entirely, with the second windinglayer; a dielectric package for at least radially containing orbordering the first winding member and the second winding member; afirst metallic member having a generally planar, radially extendingsurface for electrically and mechanically contacting an upper portionthe first conductive layer; a second metallic member having a generallyplanar, radially extending surface for electrically and mechanicallycontacting a lower portion of the second conductive layer, where thesecond metallic layer is covered with a bottom dielectric member of orintegral with a lower side surface; a first lead coupled to the firstmetallic layer and extending through an upper side surface, where thefirst lead extends from the upper side surface to the lower side surfaceto terminate in a planar metallic pad outward from the bottom dielectricmember; and a second lead coupled to a lower portion of the secondconductive layer via the second metallic member and an internalconductor, the internal conductor extending through a central internaldielectric region and being spaced apart, radially inward, from thefirst winding member and second winding member, where the second leadextends from the upper side surface to the lower side surface toterminate in another planar metallic pad outward from the bottomdielectric member.
 2. The capacitor according to claim 1 wherein thedielectric package has the lower side surface opposite the upper sidesurface; the first lead having generally planar surfaces parallel to orco-planar to the upper side surface and the lower side surface; thesecond lead spaced apart from the first lead, the second lead havinggenerally planar surfaces parallel to or co-planar to the upper sidesurface and the lower side surface.
 3. The capacitor according to claim1 wherein the second metallic member is substantially planar.
 4. Thecapacitor according to claim 1 wherein the first lead terminates in theplanar metallic pad for mounting on a circuit board and wherein thesecond lead terminates in said another planar metallic pad for mountingon the circuit board.
 5. The capacitor according to claim 1 wherein thesecond metallic member extends radially outward from a central axis ofthe package.
 6. The capacitor according to claim 1 wherein the firstlead and a second lead extend radially outward diagonally from or nearthe central axis of the package.
 7. The capacitor according to claim 1wherein each one of the first winding member and the second windingmember has a substantially spiral cross-section of its respectiveconductive layer.
 8. The capacitor according to claim 1 wherein thebottom dielectric layer is generally elliptical.
 9. The capacitoraccording to claim 1 wherein the first lead extends from the upper sidesurface to the lower side surface outside of or on an exterior of thedielectric package and where the second lead extends from the upper sidesurface to the lower side surface outside of or on an exterior of thedielectric package.
 10. The capacitor according to claim 1 wherein thesecond lead extends through the upper side surface such that the firstlead and the second lead are spaced apart to provide two separateelectric terminals of the capacitor.
 11. An electronic assemblycomprising: a circuit board having one or more conductive traces; acapacitor for mounting on the circuit board, the capacitor comprising: afirst winding member comprising a first dielectric layer and a firstconductive layer, the first conductive layer overlying the firstdielectric layer; a second winding member comprising a second conductivelayer and a second dielectric layer, the second conductive layeroverlying the second dielectric layer, the first winding memberinterleaved, partially or entirely, with the second winding layer; adielectric package for containing radially or bordering radially thefirst winding member and the second winding member, the dielectricpackage having an upper side surface; a first metallic member having agenerally planar, radially extending surface for electrically andmechanically contacting an upper portion of the first conductive layer;a second metallic member having a generally planar, radially extendingsurface for electrically and mechanically contacting a lower portion ofthe second conductive layer, where the second metallic layer is coveredwith a bottom dielectric member of or integral with a lower sidesurface; a first lead coupled to the first metallic layer and extendingthrough the upper side surface, where the first lead extends from theupper side surface to the lower side surface to terminate in a planarmetallic pad outward from the bottom dielectric member; and a secondlead extending through the upper side surface, the second lead coupledto a lower portion of the second conductive layer via the secondmetallic member and an internal conductor, the internal conductorextending through a central internal dielectric region and being spacedapart, radially inward, from the first winding member and second windingmember, where the second lead extends from the upper side surface to thelower side surface to terminate in another planar metallic pad outwardfrom the bottom dielectric member.
 12. The electronic assembly accordingto claim 11 wherein the dielectric package has the lower side surfaceopposite the upper side surface; the first lead having generally planarsurfaces parallel to or co-planar to the upper side surface and thelower side surface; the second lead having generally planar surfacesparallel to or co-planar to the upper side surface and the lower sidesurface.
 13. The electronic assembly according to claim 11 wherein themetallic pads are soldered to corresponding mounting pads on the circuitboard.
 14. The electronic assembly according to claim 11 furthercomprising a plurality of said capacitors; wherein said plurality ofcapacitors are arranged in one more rows on the circuit board.
 15. Theelectronic assembly according to claim 11 further comprising a first setof the capacitors mounted on a first side of the circuit board and asecond set of the capacitors mounted on a second side of the circuitboard opposite the first side.
 16. The electronic assembly according toclaim 15 further comprising: an enclosure having a first enclosureportion for engaging or contacting first leads and second leads of thefirst set of capacitors and a second enclosure portion for engaging orcontacting first leads and second leads of the second set of capacitorssuch that heat can axially flow away from the electronic assembly viathe enclosure.
 17. The electronic assembly according to claim 11 whereinthe bottom dielectric layer is generally elliptical.
 18. The electronicassembly according to claim 11 wherein the first lead extends from theupper side surface to the lower side surface outside of or on anexterior of the dielectric package and where the second lead extendsfrom the upper side surface to the lower side surface outside of or onan exterior of the dielectric package.
 19. The electronic assemblyaccording to claim 11 wherein the second lead is spaced apart from thefirst lead to provide two separate electric terminals of the capacitor.